The type initializer for 'Microsoft.Crm.FeatureControlChecker' threw an exception - CRM 2011 attempting to install Rollup 18

Hello, 

I'm attempting to install rollup 18 on CRM 2011, but see an error message "The type initializer for 'Microsoft.Crm.FeatureControlChecker' threw an exception"

The type initializer for 'Microsoft.Crm.Locatorservice' threw an exception.

Unable to initialize the native configuration support external to the web worker process (HRRESULT=0x80040154). natived.dll must be in %windir%\system32\inetsrv.

Any thoughts why this is occuring and how to resolve?  thanks